Modern email systems are amenable to email messages in either a plain-text format (e.g., American standard code for information interchange (ASCII)) or an encoded format (e.g., hyper-text markup language (HTML), multi-purpose Internet mail extension (MIME), etc.). While plain-text email messages are sufficient for simply conveying message content to intended recipients, these plain-text email messages provide very few options on how the email messages are displayed due to their limited functionality.
Conversely, email messages in encoded formats have greater functionality. For example, HTML-formatted email messages may include bitmap images that are directly embedded into the email message itself. Thus, when a recipient receives the HTML-formatted email message, the embedded bitmap image is automatically displayed to the recipient in an email read window.
While many of the embedded items in encoded-format email messages are harmless, the ability to introduce self-executing code into encoded-format email messages results in a greater susceptibility of encoded-format email messages to viruses, worms, Trojan programs, etc.
Thus, a heretofore unaddressed need exists in the industry to reduce the susceptibility of encoded-format email messages to undesired executable programs.